This invention relates to a thermal line scanning instrument, and more particularly to such an instrument which generates a single thermal line scan and displays the thermal profile thereof superimposed on a visual view of the target.
Infrared thermography has been employed extensively for remote temperature sensing and is being utilized in many applications for non-destructive testing of materials and processes, etc., and for diagnostic purposes as well as many other applications. Use of an infrared camera in many of these applications provides a thermal image of the entire target area where, in fact, only a small area or spot of the entire target area may be of interest. It is believed that an infrared camera is used in such applications in order to orient the camera on the subject or target and to identify the objects whose temperature is desired to be examined. For those applications where the IR camera is used primarily to physically locate a small area of interest on the target surface, the expense, bulk, complexity, or other disadvantages in such an application may inhibit the use of the infrared approach.
One approach to the problem is shown and described in U.S. Pat. No. 3,641,348 entitled "Thermal Imaging System with Thermal Image Superimposed on a Target Scene," which is assigned to the assignee of the present application. In this approach, the field of view is scanned by a Nipkow scanner and applied to an infrared detector which modulates a light source in accordance with the intensity of the radiation applied from the field of view which is scanned. The intensity modulated light source is imaged through the same reticle and superimposed on the sight of a viewing telescope. Looking through the telescope a view of the target scene is presented with a red tinge in the regions in which the target is warm or overheated. This system requires a rotating reticle, and also provides for the scanning of the entire target area. Quantitative data with respect to the temperature displayed is not easily interpreted by viewing the target scene in which the temperature is provided in the form of a red tinge. Although the hotter areas would have a brighter tinge than the cooler areas, the differences therebetween would be difficult to interpret.